Isner KO helps Spain progress
John Isner's withdrawal with a knee injury sent Spain through to the final of the Hopman Cup where they will face either Serbia or Australia.
Isner's late pull-out cost the United States any chance of reaching the Saturday final, as opponent Fernando Verdasco was awarded a 6-0 6-0 walkover success.
Speaking on court, Isner, hampered all week by what he had earlier described as "a bit of tendonitis", said: "I'm very, very sorry to all the fans here. I really wanted to play here against Fernando, so I apologise for that and I hope you guys understand."
Hosts Australia gave themselves hope of facing Spain in the final after 16-year-old Ashleigh Barty scored a magnificent 6-0 6-3 win over Italy's former French Open champion Francesca Schiavone.
Barty, the world number 175, needed just 55 minutes to polish off her opponent and give Australia an unassailable 2-0 lead in the tie after Bernard Tomic's earlier 6-3 7-5 win over Andreas Seppi.
However, Serbia remain favourites to reach the final and will do so if they make it three wins out of three against already-eliminated Germany on Friday. Failure to do so will send Australia through.